Rheology of oil-in-water emulsions containing fine particles

The effect of fine solids on the viscosity of oil-in-water emulsions was investigated. The emulsion–solid mixtures were prepared from oils having viscosities of 20, 60, and 220 mPa s with the addition of 0–2% particles. The relative viscosities of the emulsion–solid mixtures were functions of the oil and solids, and the shear rate. General equations commonly used in the literature could not predict the viscosity of the emulsion–solid mixtures. The relative viscosities at high shear rates (≥450 s−1) could be correlated by ηr=exp[(b×ln(ϕo)+c)×ϕs], where b equals 85 and c ranges from 195 to 208.